The present invention relates in general to a safety device for sheet-fed offset printing presses and in particular to a safety interlock/latch assembly for use with a guard element on the printing press.
Printing presses include numerous rotating cylinders/rollers which are well known in the prior art and may have various safety devices which are adapted to be used in connection with oppositely rotating cylinders/rollers. A pair of such oppositely rotating cylinders/rollers define between themselves a contact gap where the cylinders may, for example, directly engage each other or where they engage a sheet material which passes between and in engagement with such cylinders. These cylinders have parallel axes and, if present, the safety device will generally include a swingable switch actuating assembly turnable about an axis parallel to that of each cylinder/roller and co-acting with a control current limit switch in order to limit the operation of the machine when the safety device is moved away from the cylinders/rollers. Other safety devices have plates and barriers which protect an operator from various portions of a printing press when it is in operation. In general, such a device will be referred to as a "guard element".
It is also known that operators have purposely defeated various guard elements to make it easier to perform the many servicing functions required for operation of the printing press, such as, removal of components for cleaning and/or major maintenance. However, disabling the guard elements has led to accidents for the operator of such printing presses. In the prior art, if interlocked when the guard element is in a closed or protective position a limit switch is engaged and correspondingly when the guard element is moved out of the protective position the limit switch causes the printing press to stop. However, prior art safety devices including the limit switches have been easily by-passed by the operators.
The present invention overcomes these drawbacks in the prior art and provides a safety device or safety interlock/latch assembly for use with a guard element on a printing press which protects the operator and allows for easy removal and replacement of the guard element, and increases the probability that the operator will be unable to bypass the safety latch assembly.